Automatic telephone-exchange system.



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A. E. KEiTH L T. G. MARTIN.

AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED DEC. 20,1906.

A E KEITH & T G MARTIN AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED DEC-20. 1906.

Patented Aug. 24, 1915.

3 SHEETS-SHEET 2.

I mmwg A. E.' KEITH & T. G MARTIN.

` AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED DEc.2o. |906.

'Patented Aug. 21, 1915.

3 SHEETS-SHEET 3.

mamie. f

CHICAGO, ILLINOIS T all whoi'iifjit may concern;

l Be it known thatwe, ALnXANDr-RE. KEITH and TALo'r-G. MAR'ri'Njbotlrcitizens of the phone exchange systems, ,but more particulai-ly te partyline exchanges, and especially to coinnion'battery exchanges in whichthe party' lines are provided with individual switches for automaticallytrunking calling subscribers yinto. connectign with idlefirstselectors,f ,our invention broadly contemplat-I ing a'systemcharacterized by these features, ih combination withthe featureof a lockout,l arrangement vfor each party line sub-v scribeiywherebyone subscriber cannot interferie .with another in the use of a partyline. To the.foregoing andvother useful ends, ouriinvention consists inmatters hereinafter set forthand claimed.`

In tlfe' accompanying drawings, Figure -1 isa diagrainmatioviewrepresenting an established connection of the switchingapparatusinvolved when one subscriber calls an- -otherfsubscriber on hisown line. The subscribesline terminates in the line switch A1 at thecentral oilice, where the battery B isflocated'ihat provides' currentforboth calling and talking purposes.. As shown, the said battery has itspositive" terminal preferably Agrounded at. G. The said- `line switch isrepresented as having connected fwitli a selector-switch C, andv theselector with the :connector I), the latter having called back upon thecallingV line across which arebridged the substations E, F and. II.; Ebeing the calling stationand H the 'calledstation. VThe central voiificebattery B iis shown-'in the various drawings, but there is'in'fact butone battery. The line switch, being of the general type'describedpatent' application Serial No.' 311,327, is controlled for selective.purposes by the so-' y 'calledsniaster switch I. The line switchesareall arranged in groups'o, usually, one' hundred, `each hundred' beingcontrolled by an allotted master switch.- Figi 2 is also a. diagrammaticview showing the more important operative details of.' the line switchiran sra'rns ra'rnnr onirica. anexar-Inseln. KEITH .ann TALBorG.iviARTIN; orcI-IIcAGo, ILLINOIS, Assis BY-MESNE ASSIGNMENTS, To FIRSTTRusrAND LsavINcrs BANK TRUsTE-,if'or Our `invention` relates toautomatic tele-- AUTOMATIC TELEPHONE-.EXCHANGE SYSTEM.V

, rau-.mea aug. ai, 1915.

Application filed December 20, 1995. Serial No. 348,769.

A and of the master switch I and the circuit connections between saidswitches.' Fig. 3 is a diagram of the' connector.

i The substation may be of any suitable or Y approved type. Thesubstation E, for instance, like all the other substations in thesystem, may be of the general type described in patent applicationSerial No. 278,901.

The substation E, for instance, is provided 'with 4a receiver '2 and aswitch-hook 3, which latter has radiating from its body a number v ofcamv arms 4, 5 and'G, the cani arm 6 being provided with an insulating-tip 7. Said hook is suitably pivoted on tlieso-called substationkeyboard frame. which carries most of the mechanical details oftlie'telephone.

Ars-usual, t-lie switch-hook is raised or low-" land secondarywindings11 and 12, respectively; also a couple of condensers 13 and 11, asignaling device composed of a pushbutton 15, a spring 1 6, and two'contact points 17 and 18, vwhereby one side of the mainline maybeg-rounded: and in addition a relay 19 under the control of which arethe springs 20, 21, 22 Vand 23. Then the switchhook is down the cam arm5 is held in contact with the spring 24,- whereby7 said spring is atsuch time retained in a downwardly flexed condition. Said spring and camarm are, therefore, normally in contact, and inthis way a circuit iscompletedfrom the ,line through the ringer 9, which circuit includes,beside the ringer 9,'the ringer cir cuit spring24 and condenser 13.

Associated withtlie ringer circuit spring 24 are two sets of springs26and 27, and 28 and 29. The members of each of these sets, when left totheir own tensionthat is,

Furthermore, saidwhen the switch-hook is up-engage with f each other,the springs 26 and 27 being in contact, and the springs 28 and 29 beingalso in contact; and whenever the switch-hook depresses the spring 24the springs 27 and 29y separate from the. springs 26 'and 28respectively. -The cam arm (f3- controls the vsprings 3 0, 31, 32 and 33vof Whichtheinem-- normally resting in front of' a pin on the eXtremityof the dog 46 so that it is, impos-A bers 30, 31 and 3 1re normallyretained-out ot engagement th each other, and the spring 32m. co actwith the fourth spring 33; but whe switch-hook is up the first threesprmgsare forced together by the said cam arm 6. Furthermore, whiletheswitchhook lis `down the springs 34 and 35 are kept f apart by thesaid cam arm 6, but after the switch-hook rises vand the dial is turned,the said springs flex .into contat/t. There are three other springs 36,37 and 38 under the control ofthe cam arm 4, which springs are known asthe release springs,`and which are forced into engagement by the saidcam arm whenthe latter engages a laterally projectl ing piece 39 attheupper extremity of the spring 38. However, when the switch-hook nearsits lower-most position said arm dis engages from said springand permitsthe said release springs to again disengage. The calling device inthisst1bst1`tion\ comA prises an` impulsewheel 40 which is provided withso-called Vertical limpulse teeth 41 and with a rotary impulse tooth 42,the

former being adapted to operate the vertical'iinpulse spring43, and thelatter the rotary impulse spring 44 with regard to the ground post 45,whereby ground impulsesl are transmitted tothe line for operating thecentral oiice apparatus. Normally, the impulse wheel and dial arellocked by the locking cam 46 and the dog 46, the former sible to rotatethe dial. The substation relay 19 is suitably mounted upon the keyboardor switch-frame. This relay is provided with an armature 47 by means ofwhich,` when the relayv is magnetized, the springs 20 and 22 areseparated from the springs 21 and 23, respectively.,- Furtherthe relayframe. l metal piece is bent .upwardly and also at a more, saidlrelayhas on its vunder side an armature locking device that consistspreferably of a metal piece48 which is riveted to -a spring 49 that isfastened'to the rear of The `front. end of 'said right angle to thefront; and whenever the armature 47 is attracted bythe magnet thetension 'in the spring 49 forces the metal member upwardly until theangled section rises in` tront of the armature 47, lockingv the latterinits attracted position, as shown at' substation F. The switch-hookalso carries a small link rod 50 that extends to the front of the relay.The lower end'of said link works in front of the armature '47' and isbent horizontally at a right angle and ina plane parallel to the planeof the armature.

When-the switch-hook isdepressed, the said'- link v50v descends farenough-to drive' the lock 48 below the edge of the armature 47,

which latter then, if the magnet is not ener.

gized, resumes its normal position, as'shown yat substation E in Fig. 1. When the saidy \\rmatur e is restqred the 'relay springs 2O and21, 22 and 23', ofcourse,- rengage.

The line switch A is' built upon a suitable frame 'and comprises aplunger '51'and -a plunger arm 52. It is also equipped with a cut-offrelay 53 and trip magnet 54 andtheswitch release magnet 55. -The'saidmagnets may be secured to the switch frame by anymeans known to the art.The said release magnet 55 1s provided with'an armature 56 that ispivoted to a pin-,57, the latter which the armature 59 oscillates, isycarried on a bifurcated terminalfof the armature 56.

.The plunger 51 'is pivotally' secured by a pin 62 to the plunger arm52, which latter is in turn'piv'otally held in place by -a pin 63. Thesaid line switch is provided with a bank of terminals, usually ten innumber, only one of which is `shown at J. fis shown in' .Fig.-2, thesaid terminal 'J is distorted from its tru'e position withrespectto theswing of the plunger 51. The terminal J comprises the springs 64 and 65,66 and 67, l

66 and 69, '70 and? 1. The said springs are normally'disconnected fromeach other, and

when. the plunger 51 yoperates are driven into contact in the followingorder: 64 and 65,66 and 67, 68 and 69,4 and 7() and 71.4

Normally, the plunger 51, however, is retained out'of engagement with'the line switchbank and in engagement with the plunger-controllingshaft 72, which latter is operated by the master switchl The saidplunger .is thusheld by the armaturey 59 of the trip magnet54`, whichlatter is provided with a terminal'73 adapted to engage the rearterminal 74 of the plunger varm 52 in opposition to the'tension of theplunger arm spring 75. The vcut-off relay 53 is provided with. a vcoupleof springs 76l and 77 for controlling the energlzing cir# cuit of thetripmagnet a The operation of the line swltch A 1n general is asfollows: Y'Vh'en the subscriberv removes his receiver from theswitch-hook,-r as the latter rises a preliminary impulse-is .120 sentfromthe'substation that energizes thetrip magnet `54 for al moment,whereby thev armature 59 is attracted and the catch 'disengaged from thep-lungerarm 52j; then the 'spring Z5-rotates the said.l arm; 52 aboutthe pin 63, and if the position of the plunger shaft 72 is such that theplunger 5151s'A opposite the terminal'J the said'plunger is thrustbetween the terminal-springs 7 1 'and 'd l 64, whereby the terminalsprings farecloszedv .v3

into Contact, as alreadycclescribed.v The plunger shaft 72 is providedWithva longigfwtudinal channel 77 in which all dlevplungers normallyrest, When the Aplunger is brought ir'ito use it may be restored by amomentary energization of the release magnet 55, )vhich occurs when thesubscriber hangs up his receiver and grounds both of `his lineconductors simultaneously. In such event the release magnet attracts therelease armature 56, whereby the armature 59 is raised sufficiently topermit the catch terminal -73. to drop into normal engagement with theplunger arm 52; thenwhen therelease magnet denergizes,the plunger 51 isWithdrawn from the bank and carried into engagement with the shaft'7 2.It .will be understood that the rotary motion of the pass without therange of the rear terminal plunger shaft-is a backward andforivardmotion, and at no time does the channel 77- 7 8 of the plunger 51. v

The master switch-I is provided for operating the plunger shaft 72 Aandfor controlling certain circuits that will be disclosed. It is acomparatively simple switch,.having the following details: .a motormagnet 79 for operating the ratchet wheel 80, a dif.-

, ferential relay 81 'and an auxiliary relay 82,

the former controlling the energizing circuit of the motor magnet 79,and the latter the energizing circuits of all 'trip magnets 54, of lineswitches controlled by said master switch. bank K comprisingafpluralityof individual contact segments'a fand @metallic seglment. 83 common tothe said segments, as

shown in'Fig. 42. The Wiper 8l is adapted to remain inconstant'engagement with the banky K, and t0 at all times maintain someone of the segments a in electrical connection with the common segmentl83. The wiper .Sl is operated in astep-by-step manner by ythe pins 8.6,87,

the ratchet Wheel 80, through the 'medium of a cam member rigidlysecured to the said wiper 8l and adapted to successively engage 88 Vand89 upon the said ratchet Wheel 90. The said Wipere and 'cam `member 85are, as shown, rigidly connected to one headof'the plunger, shaft 72.

The motor magnetv 79 is provided with an armature 87 upon the end ofwhich there is suitably secured a pawl 90. Each time that the saidmagnetis'energized the pawl 90 engages the ratchet Wheel 80, advancing thelatter one step. It .will therefore be noticed y .that asthe ratchetwheel' 80 advances in a counter-clockwise direction, the Wiper 81advancess'tep-by-step from right to left; and when the pin S6, 'forinstance, clears the cam 85 the retracting spring 91 restores the Wiperl84 to its first position at the right of the l bank K in'engagementwith the first segment'92. The said motormagnet 79 is provdedwith acouple of interrupter springs The saidjgnaster switch also has-aconductors 93 and 94 that are luded in the energizing circuit of theSaid-'motor magnet, which energizing circuit also lcomprises the springs95 and 96 controlled by the differentialre lay 8l. Therefore, Wheneverthe differential relay 81 is energized the springs 95 and A96 arepressed into-contact and the motor magnet 79 operates stepbystep as'long asthe differential relay 81 remains energizec Furthermore, it isassamed thattheterminal J of the line svitch A is thefirst terminal ofthe "line Switch bank, and therefore the plungerl is retained Vin frontof said terminal by the plunger shaft '72 whenever the master switchlWiper 8l is in engagement .With the bank segment 92; but as the motr`magnet 79 advances the Wiper 8l onto the second segment 97, all idleplungers are carried oppositethe next terminal of the line switch bank.in each line switch bank all of the springs are permanently connectedandvinafv be made of one common piece; the springs 69are,however,individual*that is,'. there is `one separate and` distinctspring for every conductors 104 and 105 vterminate .in thev springs 6land 66 which, as has been stated, are common springs. The vertical androtary trunk 'conductors 98v and 99 pass. through the vertical andArotary private nor vmal Vrelays 106 and 107. 1espectivel v.and theserelays control the connection between vground and the 4private normalconductor 103 through the medium of the springs 10S,

109, 110'and 111. When the subscriber opcrates the line switch A, andthe plunger engages the terminalv J, the subscribers line 101 and 105are extended through-the private normal relays 106 and 107 to thevertical and rotary trunk con# ductorsv 98 and 99, and thence to thelselector switch C. v a

The first-selector may be'of any suitable'or approved type,vsuch as theselector described in United States Patent No. 815,321, granted March13, 1906, to Keith, `Erickson and Wipers 112 and\1'13.` and the privateWiper 114,1 are attached. The'said switch-shaft is lt should be `notedthat' Erickson. It comprises a switch-shalt't(notv i Y shownlto-vvh-ichthe verticaland rotary line controlled by the calling subscriber throughi the medium of the vertical and rotary line relays 115 and 116. TheV*former-fisfadapted v to operate the vertical magnet 117, which magnetis designed to impart to' the switch-K,`

shaft its vertical movement.v

rlhe private magnet 118 is controlled by the rotary line relay 116, saidprivate magnet having con-` fvtrol of the well-known side switch thatcomprises the side switch wipers 119, 120, 121

. y passes tothird position, but the selector be- 1.515` c r switchpasses to third position the release ing of the trunk-release type, whenthe, side magnet 124 is controlled from vthe next switch by means oittlie'back-1elease relay 125 in a. well-known manner.

The connector switch D is ot the general type described in United StatesLetters Patent No. 815,176, granted March 13, 1906, to f Keith, Ericksonand Erickson.

u nector switch-shaft 12.6 carries the switchshaftwipers 126, 127 and128. rfhe said connector is controlled by the calling subscriber`through' lthe medium of the vertical and rotary line relays 129 and130. The vertical Y line -relay 129 is employed for controlling and 132,which magnets 131 and 132 in turn both the vertical and rotary magnets131 impart to the switch-shaft and lwipers their vertical and rotarymovements. The rotary line' relay 130 controls the private magnet ,1133,which latter in turn controls the posi- .tion of the connector sideswitch L, which Sidevswitch is provided with the wipers 134,

135,136and 137. The connector side switch,

l l.like the side switch of the first-selector, nor- 40 mally rests in aposition known as the rst position of the side switch, and may beshifted tov second and third positions by the operation of the privatemagnet. The vertical and rotary line relays 129 and 130 may be used`conjointly by the calling subscriber Y or energizing a release magnet'138. The

nergizing circuit for said release magnet s retainednormally open by theconnector ifferential relay 139,' which relay is proided with twowindings 140 and 141. Then y he said differential. relay energizes itcloses the 'connection between the release magnet and the non-groundedterminal of the battery. Said differential relay also controls 55 theenergizing circuit of the rotary backlbridge relay 142 and of thevertical back-l bridge relay 143 when the called subscriberl Inaddition, the connector" has answered. hast-he usual ringer relay 144.lThrough the medium of the ringer relay springs 145, 146, 147, 148, 149and 150,.saidringer relay is adapted to disconnect the callingsubscribers line fromv the called subscribers -2line, and to bridge thelatter across the ringer generator 151. The said ringer relay has inaddition a couple of springs 152 and 153, whereby when the said ringerrelay is energized the normal bridge across the main line that existsthrough the vertical and rotary line relays 129 and 130 isopened inorder to -prevent ringing current from interfering with the connectorwhen the said connector calls back on the calling line.

In the exchange there is also a busy signalingl however, precedes theoperations of the calling device corresponding to the digits. Saidimpulse is transmitted when the hook spring 155 engages the groundspring 156, as the subscriber Vremoves his receiver 2 from theswitch-hook 3. As a result the' trip magnet 54 or' the line switch A isenergized by a flow. of current from ground G1 to the springs 156 and155, thence tothe switchhook 3 and to the rotary line conductor 105,conductor 157 (Fig. 2), cut-ott relay springs 76xand 77 to the tripmagnet 54, thence through said tripmagnet to the conductor 158,auxiliary relay springs 159' and 160 to the battery lead 161, thencethrough battery B to ground G. As soon as the trip magnet 54 energizes,the armature 59 is attracted and the plunger 51 is liberated and thrustinto the bank terminal J by the spring 75. At the instant that the saidplunger 51 enters the said bank position J, the following springs arepressed into contact: 64 and 65, 66 and 67, 08 and 69, 70 and 71. Theengagement of the springs 70 and 71 establishes a circuit from ground G2by way of the normal conductor 103 to the connector nector privatebanks. The closure of con nection between the springs 68 and 69 alsoestablishes a guardingpotential at the mas ter switch bank Contact 92over the following circuit: from battery B to the battery lead 161,thence to the release magnet 55 and through`the said magnet and springs68 and 69 over the conductor 163 to the said contact point 92. It willbe understood that the bank terminal J, being the first insignia4bank'terminal of the. line switch banl'r, corresponds to the firstsegmenti?? ot the mas ter switch lbank K. At the instant that the saidguarding potentialA is established the masterswitch wiper '84 is restingupon the contact point v92, thereby closing a circuit between the saidContact and the common plate 83.01: thebank K, whereby an energizingcircuit is established for magnetizing the auxiliaryrela-y 82 andthedifferential relay 81 of the master switch'. The current through thesaid relays liows from the said contact 92 'through the wiper-'81 to thecom- 1'64 through the auxiliary relay '82,V and through the winding 165of the' auxiliary relay 81 to ground G3. Then the diierential relay 81-attra'ctsits armature the diiferential relay springs 95 and 96 arepressed into contact,;`tliereby closing the energizing. ,circuit for themotor magnet '79 from ground Grl through the said .springs 96 and 95 tothe motor magnet 79, 'thence through the said magnetand through theinterruptei' springs 491' and 98 to the battery lead 161.,

and through battery to ground 1G. The .'motor magnet then operates torotate vthey ratchet wheel 80 one step for advancing the plunger shaft79. one step and the -master switch bank wiper 81 one step also. intoengagement with the second segment 97. The plunger shaft 72, when thusadvanced one step', carries all idle plungers that are lin engagementwith the said sha-ft opposite the next bank terminal (similar to the:terminal J), which corresponds to the segment 970i the masterv switchbank lx. 1f there lshould 'be a guarding .potential at the bank segment97 ot' ,the master switch the differ- 'ent-ial relay 81 lwill remainenergized after the motor magnet armature 87 returns to normal positionand again closes connection between the springs '93 and 94, and as aresult-the motor magnet 79 is again operated, whereby the plunger shaft72 and the master switchvwiper184 are advanced another step. Thisprocess continues as long as the vwiper 8-lco1itinues to find segmentswith guarding potentials.

As soon as an idle segment. is lfound, the energizing circuit throughthe differential relay 81 is broken,

at which 'time the said relay in turn permanently'breaks the energizingcircuit for the motor magnet 79 until the next subscriber makes a call.

l-'lt will be noticed that the energizing cir cuit'for the trip magnet54 is controlled by the'auxiliary relay As a matter of fact, and -asalready stated, all the trip magnets 'of the line switches in the sainegroup are cont-rolled by the said springs 159 and 160,

whereby, when the auxiliary relay `82 isV energized, no'fline switchwill be able to trip and seize a triunk line until the wiper 8l of themaster switch iii'ds an idle segment.

Amon segii'ient 83, thence over the conductor The object inth'usarranging the 'circuits of the trip magnets .is to prevent anylsubscriber from tripping lin hisA allotted .line switch onto a busytrunk 'if he shouldl call' while the auxiliary relay ,82 is. energized,

and, of course, while the wiper 84 is passing .through tlie'said relayto the vertical'trunk conductor 98, and thence to the sidersw'itcl'iwiper 119 of the lirst-selector C. The closure of contact between thesprings 66 and 67 in a similar manner extends thesubscrib ers rotaryline conductor 105 to the rotary privatenormal relay 107, and throughthe said relay'to the rotary trunk conductor-99, and thence to' the sideswitch wiper "120 of the selector The subscriber has thus establishedconnection with tlie selector C and is ready to .begin operating hiscalling device' for the first digit.

.The first digit being 3,the subscriber oper ates his dial accordingly,grounding the vertical line conductor 101 each time thatl the spring 43is pressed onto theA ground post #15. As a result the vertical linerelay 115 of the. iirst-selector C is energized by a flow of curlrentfromthesiibstation ground lG1 throughv the substation relay springs 22and 23, to the .ground post 15, thence through the spring 4 8 to thevertical line conductor 101line switch bank springs 61 and 65, verticalprivate Anormal relay 106, vertical trunk conductor 98, side switchwiper 119 of the selector C, contact point 168,'verticalline relay 115to thebattery lead 1.61, thence through battery B toY ground Cr. Eachtime that the vertical, line relay 115 energizes, the line relay spring169 is pressed onto the .ground spring 170. The vertical magnet 117 isthereby energized, and the wipers112, 113 and 111 of the selector '.Care raised to the ,third bank., level opposite the first contact of saidlevel. said vertical magnet 117 Vextends from ground G14 through thesprings 170 and 169,v private springs 172 and 173 to the vertical magnet117, thence to thebattery lead 161, and through battery B to, ground G.The sgring 44 is then pressed onto the ground vost l5, grounding therotary line conductor 105 and energizing, tlierefore,the rotary linerelay 116 ofthe selector C. Theenergizing rlhe energizing circuit forthe llio ' 67, rotary private normal relay 107, rotary trunk conductor99, side switch wiper 120 of the selector C, contact point 171 to therotary line `relay 116, thence through said relay. to the battery lead161, and through battery B to ground G. The rotary line relay,uponzoperating, presses the'line relay spring 171 onto the -groundspring 170,

'thereby establishing a circuit through .the

private magnet 118 from ground4 through the springs 170 and .171 to theprivate magnet 118 and through the said mag-4 net to the battery lead161, thence through battery B to ground G. The private magnet, uponenergizing and denergizing, permits the selector side switch to passfrom first to second y position, permitting theV side switch wipers 121and 122A t0 engage the -contact points 171 and 175, respectively,

The closure of connection between the side switch wiper and the contactpoint-175 sets up a magnetizing circi'it for the rotary magnet 123 fromground (1 to the contact point 17 5,'through the side sw tch wiper 122,

interrupter spring 176, rotary magnet 123 to the battery lead 161,thence through batteryB to ground G. The said rotary magnet 123 thenoperates to rotate the wipers 112, 113 and 111 `of the selector C intoengagement with a trunk line leading to some idle connector switch and,in the particular case under consideration, to the connector switch D.It the wipers have to pass over ergizing circuit for said privatemagnetex tends from an occupying switch (not shown) to the private wiper 111,thence over the conductor 177, and through the baclbrelease relay 125 tothe side switch wiper 121, contact point 171, private magnet 118, thencethrough said magnet to the battery lead 161, and through battery B toground G. The private magnet 118, upon thus becoming energized, locksthe side switch wiper 122m engagement with the grounded Contact point175, whereby the rotary niagnet 123 will be energized step-by-step untilthewipers are carried beyond the. last busy trunk line. At the instantthat the privatewiper leaves the last busy contact point, the energizingcircuit through tlie private magnet 118 is destroyed, and as a resultthe selector side switch passes to third position. 1f, however, thereare no busy trunk-lines, the pri.- vate magnet 118 releases the sideswitch to third position as soon as the wipers are carried intoengagement with the'irst trunk line. As soon as the side switch passesto third position, as stated, the subscribers line conductors 101 and10`5are extended to the;y

idle connectorswitch which, in Athis case, .it is assumed is theconnector switch D. .The

extension ofthe line'occurs as soon as the side` switch wipers v119 and120 engage the contact points 178 and 1.79', respectively.l "Notvonly isthe subscribers line thus extended,l' utra guarding potential isestablished I vat the private wiper 111, when'the side switch wiper 121passes onto-the grounded contact point 180, for protecting the seizedtrunk line 'from interference by other calling subscribers. Thisguarding potential is established fromI ground GG to the contact point180,' thence through'the side switch wiper 121 and through the,back-release relay 125 to the private wiper 111. It will be,

necessary, of course, that the energizing cirenit for the rotary vmagnet123, to which rer'- erence has alreadybeen'made,v be destroyed when theidle trunk line is seized., and therefore when the side switch wiper 122'leaves the rounded contact point. in, .this energizing circuit isbroken. In the' foregoing the-energizing circuits for the vertical androtary line relays 115 and 11G have com. prised Ithe private normalrelays' 10G. and 107, as described, but the energizationjot' said relaysso far has played a part of` no significance.

The second digit of the'number beingil,

the calling. subscriber operates his dial again y.

accordingly', as a result grounding the vertical line conductor- 101when the spring 13` i meets the ground post 15. The vertical line relay129 of the connector switch D is, therefore, energized by a flow ofcurrent from the substation ground G to the vertical line conductor 101,thence throughv the line switch banksprings 61 and 65, vertical pri-'.vate normal relay 106vertical trunk con` ductor'98, side switch wiper119 of the se-v lector C, Contact point 178, vertical line 'wiper 112,vertical -trunk conductor 181, ve'rtical iine`relay 129, winding 110 ofthe differential relay 139 to the battery lead 161,

thence tbough battery Byto ground G.-

GT through the springs 183 and 182, private springs 181 and 185, sideA'switch `wiper 131,

'contact point 188', vertical magnet 131,

thence through battery-B to ground G.

The .vertical magnet 131, asis'well under-y to the desired bank level',as disclosed in the' .ing been thus operated, when: the' rotary springLilengages the ground. post the rotary line conductor is grounded once,energizing the connector rotary line relay 130 over thefollowing-circuit: from ground G vat the substation to the rotary lineconductor 105, 'through the line switch bank springs 66 and 67, rotary.private normal relay '107, rotary trunkconducto'r 99, side switchWiper, of the selectorC, contact point 179, `rotary line Wiper 113,rotary trunk 'conductor 186, rotary line relay 130,

differential relay Winding 141, 4ringer relayl springs 152 and 1,53,'baclrfbridge relay springs 187 and 188 to the battery lead 161,

thence through battery B to ground Gr.vv The dili'erential relay 139again 'energizes, but still to no effect.

gizing thecp'rivate magnet 133. The circuit established extends fromground Gr7 through privatemagnet, upon denergizing, permits theconnector side switch to pass to second .30

position, shifting the side. switch Wiper 134 into engagement with thecontact point 191.

vThe rotary magnet 132 is: thus substituted for the vertical magnet 131to the control of the vertical line relay 129.

The third digit of the desired number. being 0, the calling subscriberoperates his dial to ground the vertical line conductor 101i ten times.4As a result the vertical line relay 129 of the connector D is energizedten times, and the line relay springs 182 and 183 operated accordingly.The rotary magnet 132 is energized overacircuit extendlng from ground GTthrough the line relay springs 183 and 182, private springs 184 and'185`side switch wiper 134, contact point 191 and the rotary magnet 132 tothe battery lead 161. thence through battery B to ground G. The saidrotary magnet then operates to rotate the shaft wipers 126, 127 and 128step- -by-step onto the tenth contact of the first level of theconnector bank,.from which terminal leads a trunk line that extends backto the calling subscriber-"s line. "lhe rotary line conductor 105 isagain grounded once, energizing the rotary line relay of the connector Dover a circuit that has been pointed out. The said rotary line, relaythen presses the springs 183 and 189 into contact.' as previouslyexplaineth with the result that the private magnet 133 is againIenergized. Energizing the private magnet 133 at this time produces oneof two results, namely the` release `ot the connectork side switch fromsecond to third position and establishing the desired connection, or thethe' release of 'the connector side switclr` The rotary line relay 130,`however, presses the line relay spring .189. ,A ontothe'ground spring1x83, as a result ener :of course, that the busy release does -notf'ocglcur when' a subscriber calls back onlus-'own line, las will beexplained. The busy release 70 follows only when a subscriber calls ontoa liney other than his own which i'sbusy-.ffhe former result Will befirst considered. nz'in'ielyigg n l second to third position. Therelease o ie 75, sidesWltch occurs'when the private magnet 133energizes, as .heretofore explainedwF-At 'v thev instant that the saidside switch passes to third positiomthe connector side "switch Wipersv136 and 137, havingengaged the con- 80 tact points 194L and 195, extendthe calling subscribers line conductors into connection With the normalconductors 101 ,and 10;?.

`Since the said. normal conductors 101 and l102 lead back to the callingline, it will be` evident that the calling subscriber has operated toconnect: the connector D with his .own line. It Will be remembered thatwhen :connector private wiper 128. Had the said guarding potentialremained constantly on the said contact point, it would havefbeenimpossible for the connector side swrtch'to have passed to thirdposition, as described.` ino L Instead, howeifer, the said connectorswitch would have been released. Attention has been called to the factthat the 'energizing circuit for the connector rotary l'iiie'relaj'f 130comprises the rotary private normal re- 105 lay 107and, therefore thatthe said relay energizes in unison with the connector ro# tary linerelay 130. Thatbeing thecasaand since the guarding potentialattheconn'ector private bank contacts' fromv the line 110 switch groundG2 comprises the springs 11,0 and 111 of'the said private normal relay'.107. the guarding potential is interrupted;.',-v at the ,same time thatthe connector rotary, line relay 130 operates the privatemagnet 133. Itis plain, therefore, that at thein-y Istant that the connector sideswitchxpasses' relay springs 22 and 23, ground springs 34 contact point18, spring 16, thence through the springs 26 and-2T to the vertical lineconductor 104. Grounding said con ductoi" operates the connector'vertical line `relay 129 andalso the differential relay 139 overcircuits that have been pointed out. Thev operation of the said relays139 and 129 causes the energization ofthe connector .ringerrelay144 overthe following circuit: from ground GT at the connector through thelinerelay springs 18E and 182, private springs'184 and 185, side switchwiper 134,

contact point 198, ringer relay ,144, thence maybe arranged to draw itsringing current.y

from a ringer generator 151. that furnishes "current of such character'that only the ringer 202 of the substation #310 willbe.

operated by said current, ivhile the ringers of all other substations onthe saine line may be so tuned that they will not respond t'o thecurrent from said generator. Simi- 'lai-ly, the' connectors of the twohundred group, which 'are employed when members.

of this group are: called, may beV arranged toidraw their ringingcurrent from a ringer generator that furnishes current of such characterthat' only ringers tuned to respond to their current will beoperated.rLikewise,

the connectors of the one hundred` group may in turn draw their ringingcurrent, from still another generator that supplies current' ot' suchcharacter that 'only those ringers that-are correspondingly tuned willoperate. It is ev'ident, then, that when generator current is'projectedout on the line by the connector l) of the three hundred group only theringer 202 will be operatively affected. The path of the ringing currentis as follows: from the ringer generator 151 through the -ringer relaysprings 150. and 149,-` side switch wiper 136, vertical normal conductor101, vertical line conductor 104, condenser" 196, ringer 202 atsubstation #310 back vto the rotary line conductor 105, thence, over Ythe rotarv normal conductorl 102, ringer relay vsprings 146 and 147 y tothe ringer generator'll again. The subscriber at substation #310 uponresponding bridges his transmitter 203 and primary winding 204 of theinduction-coil-205, in multiple with the transmitter 8 of the substation#110 and the primary winding 11 of said substation, across the lineconductors 104 and 105.

lVhen the connector side switch passes to y rotary normal. conductor102, rotary line conductor 105springs 30 and 31, substation relaysprings 21 and 20, transmitter 8, prmary winding A11, contact point 17,spring 16, springs 26 and 27, vertical line conductor 104, vertical.normal conductor'lOl, vertical line wiper 126, contact poi-nt 194, side'switch wiper 136, ringer relay springs 149 and 148, verticalback-bridge coilj143 to the battery lead 161, and through battery B toground G. The rotary back-bridge relay, upon energization, presses thesprings 187 and 208 into engagement, -thus connecting battery B acrossthe same lineover another circuit as follows: from ground G8 through therotary` back-bridge relay springs 208 and 187, ringer relay springs 153and 152, winding 141 of the differential relay 139, rotary line relayl130 to the rotary trunk conductor 186, and. through the` selector C andline .switch Ay to the rotary vline conductor 105, thence through thesubstation #110, over circuits 'already explained, to the verticallineconductor 104, thence through the 4vertical line relay 129 otth'econnector D, and winding 140 of the differential relay 139 to thebattery lead 161, thence through .battery By to ground G. The calledsubstation #310, of course,

also draws current for-talking from the line.

Both of these circuits for supplying talking current are not necessarywhen the subscriber calls another subscriber on his own line, but itwill be evident thatthey are necessary when he calls a subscriber onanother line, in which-case the first of said circuits which is thuscontrolled by the calledv subscriber is setup.

Then thea-called subscriberanswers hel provideshimseltl with talkingbattery current, and as aresult the second circuit is then established,giving battery current to the calling subscriber upon the energizationof the rotary back-bridge relay 142.4 Vhen the called subscriber removeshis receiver 209, as shown in Fig. 1, the switch-hook 210 upon risingpermits the springs 211 and 212 and the springs' 192 and 193 to engagebefore the springs 213 and 214 disenga'ge, in

lsprings 214 conductor 101, Vertical wiper 126, side switch wiper 136,ringer relay springs 149 and 148,.yertical back-ridge rcoil 143 to thebattery lead 161, thence through battery 'B to ground. G. From the saidVertical line conductor 104 there leads a multiple circuit through theline switch bank springs 64 and 65, vertical private normal relay 106,verti cal line relay 129 of the connector D, winding 140 of thedifferential-relay 139 to the battery lead 161. The* substation relay215, upon energizing, attracts and locks its armature in the same manneras described in connection with substation relay 19. Had the callingsubscriber called a subscriber on a different line, the former cir? cuitwould, of course, not eXist, since in that case the normal conductors101 and 102 would not be in multiple with the line conductors 104 and105. When the substation relay 215 energizes, the springs 217 and 218separate and the springs 219 and 220 also separate, the former twodestroying the connection between the substation ground G9 and l theground spring 221, so that the said subscriber is deprived of the. meansfor grounding either of the line conductors 104 or 105. When the springs219 and 220 separate, the normal circuit supplying current for thetransmitter 203 is broken, and a circuit is substituted that comprisesthe winding of ythe substation relay coil 215. A normal circuitsupplying current for the transmitter 8 of the substation E extends fromthe rotary line conductor 105 through the springs 30 and `31 at saidsubstation, to the springs 21 and 20 of the substation relay 19, thencethrough the transmitter8, primary winding, 11, contact point 17,signaling spring 16, primarv circuit springs 26 and 27 to the verticalline conductor 104. The springs 20 and '21 are, of course, similar tothe springs 219 and 220 at the substation H, and it will be evident thatthe circuit for supplying the transmitter 203 of the answeringsubscriber with talking battery current is different from the circuitthat supplies the transmittel' 8 with talking battery. The circuit .forthe said transmitter 203 extends from the vertical line conductor 104through the primary circuit springs 193 and 192, primary Winding 204,transmitter 203, substa- ,tion relay 215, springs 213, 222 and 223 tothe rotary line conductor. 105. The voicecurrent conducting circuitthrough the substation E is the same as thecircuit that supplies thetransmitter 8 with current, and is indicated by theheavy lineconductors.

and 213, relay 215, transmitterv '203, primary winding 204springs 192and 193, vertical conductor 104, vertical normalv the answering`substation #310'the voic'ecurrent conducting circuit 'is different/immthe current-supplying circuit, and comprises the condenser 224, asindicated bythe heavy conductors.,v The talking circuit at said sub-`station :,/:/:310.eXtends from .the Vertical line conductor 104 throughthe primary circuit Springs 19,3 and 192, primary winding 204 of theinduction-coil 205, transmitter 203 to thence through the springs 213,222 and 223 "to the rotary line conductor 105.V If, while thesubscribers #110 and :11:310 are conversing, the sub-` scriber `atsubstation #210 removeshis re- 1 ceiver from the switch-hook, thesubstation relay 225 is energized oversimilar circuits and locked in thesame manner as the relay 215 of the substation #310. The ciectof lockingthe said relay 225 produces the same results in connection withsubstation #210 that locking the relay'215 produces with respect tosubstation .#310, The subscriber at substation #210 is, therefore, madepowerless to interfere ywith the established connection, since vhisground is cut ott, as explained in connection with substation thecondenser 224,

`#310. Of course, when thesubscriber at the substation :#:210 hangs uphis receiver the link 226 is carried down by the switchhook, whereby`the relay 225 is unlocked. The same is true with respect to thesubstation #310 and the relay 215. After the subscribers are throughtalking, if the subscriber at the substation #110 hangs up his receiverhe grounds his vertical and rotary line conductors 104 and 105simultaneously, thereby `producing a release of the switches through themedium `of Which the connec` tion has been established. As theswitchhook 3 descends, the release springs 36, 37 and 38 are pressedinto contact, whereby the vertical and rotary line conductors aregrounded, as stated. The primary result of grounding theV rotary lineconductor 105 is to unbalance the differential-relay 139 by" shuntingorshort-circuiting the windingA 141 between ground G1 at substation E.and ground GrB at the connector D.

The shuntingor short-circuiting branch the side switch wiper 135, thenceto ground.

Gr?.y The differentialvrel'ay immediately ene ergizes by the .flow ofcurrent through they winding 1,40 by reason `of the ground conl nectiontothe vertical line'conductor 104.

The magnetizing current flows from substation ground G1 to the ground.release spring "36, thence lthrough the release springs 37 the releasemagnet V.in series with the vate normal relay and 38 to the yverticalline conductor 104, line switch bank springs 64 and 65, priy 106,iirst-selector side switc i wiper l 119, wiper 112 -vertical line relay12,9, winding 140 of t e differential relay through battery B. to groundG. The diferential relay 139,v upon energizing, sepa-y rates the springs206 and 207, and carries the springs 199 and 200 into engagement. Theformer of said springs (namely the springs 206 and 207), as alreadyexplained, are included in i rotary back-bridge relay 142, so that assoon aslthe said springs separate, the said relay 142 denergizes,whereby the spring 187 leaves the ground springI 208 and returns intoengagement wi h the non-grounded battery spring 188. The-.eii'ect' ofthis last operation isto remove the shunt from the 'diiierential relaywinding 141 and from the rotary line relay 130, as already described,establishing a circuit through said relay and winding, whereby acurrent-flow is set up in a reverse direction, further strengthening thedifferential relay ing the rotary line relay 130. Under these conditionsthe line relays v129 and 130 are energized, whereby the trunk-releasesprings 227 and 228 are pressed into contact, while the differentialrelay springs 199 and 200 are in. engagement, with the result that anenergizing circuit is established through 138 of the connector Dback-release relay 125 of restores up on energiz ation,

fthe side switch L and the switch-shaft 126 to normal positionin f The;energizing of .a manner fully described in connection with the connectordisclosed in said Patent No. 815,176, at which time the line and privatewipers 126, 1,27 and128 are, of course, disconnected from the normalconductors 101, 102 and 103.

the back-release relay 125 `carries the back-release relay springs 167and 166 into engagement, as a result energizing the releasev magnet 124over a circuitextending from ground G13 through the said springs 167 and166, and release magnet 124 to battery B. The selector release magnet,upon energizing, attracts its armature in readiness to release theswitch when the release' springs at the substation disengage, asdescribed in connection with the selector disclosed in jsaid Patent No.815,321. The back-release relay 125 not only energizes the magnet 124,but also the release magnet 55 .of the line switch A, since the saidrelease magnet 55 is connected.in4v

the releasefmagnet 124 of the selector A. The current through the 139 tothe battery lead 161, thence.y

the energizing circuit of the,J

139 and renergiz- `energizes, the

r' relay o3, removing release magnet 55 flows from the back-releaserelay spring 166 to the third trunk conductor 100, thence through theVAli'ne switch bank 'springs 69 and 68, through said magnet 55 to the'battery lead 161, and through battery B to ground G. When the releasemagnet 55 (Fig. 2) energizes, the armature 56 is attracted, whereby thear-' mature 59 of the trip magnet 54 is raised and the hook terminal '73 latches the terminal 7 4 of the plunger arm 52, remainin thus inreadiness to restore switch when the release magnet 55' denJ ergi'zessuliciently; A s soon as the substation release springs 36, 37 and 38separate, the energizing circuits of the rotary and vertical linerelays129 and' 130 of the connector D yare destroyed. As a result theenergizing circuit through the release magnetI 138 and the back-releaserelay 125 is broken, restoring the connector switch to normal condition.The denergization of the backrelease relay 125 in turn causes thedenergization of the selector release magnet, with the result alreadystated, and also causes the denergization of the release magnet 55 ofthe line switch A. lVhen the release magnet 55 of the said line switchderetracting spring 58,. through the medium' of the armatures 56 and 59,withdraws the plunger 51 from its operated condition into normalengagement .with the plunger shaft 72, as a result destroying, ofcourse, the energizing circuit of the cut-'off the guarding potentialfrom the master switch bank K and from the connector banks, anddisconnecting the subscribers line from the frstselector. It

' will' be clear, of course, that the private norwhich normal conductorswill, of course,

be allotted to the other line. In that event, when the called subscriberanswers, as already eXplained, iirst the connector backbridge orpole-changing .relay 142 energizes when the called subscriber bridgeshis transmitter across the line, :which relay in turn' establishes acircuit for providing the transmitter of the calling subscriber withtalking battery. In that case--thatl is, when the subscriber #110 isconnected with a subscriber of some other line-if the subscriber :#:210attemptsv to come in on the line the energizing circuit for thesubstation relay 225 does not comprise the normal conducthe individua 4CII tors 101 and 102. It will be evident, furthermore, that the privatenormal relays 106 and 107 will play no part in connection with thecalling connector, and that if the subscriber #110 calls the other linewhile said line is busy, the private wiper 128 will lind a guardingpotential'established at the connector private bank contact allotted tothe desired line. In that case,`and as already explained in saidconnector patent, the connector side svitch does not pass to thirdposition, but is released, and the calling subscriber receives a busysignal.

The busy release occurs when the rotary lineconductor 105 is groundedfor the last time and at the instant that the private magnet 133 isenergized, at which time the pri,- vate springs 229 and 230 are carriedinto 4engagement and. an energizing circuit is established through ,therelease magnet 138 as follows: from ther private bank contact to theprivate wiper 128, side switch Wiper 135, private springs 230 and 229,release magnet 138, differential relay springs 200 and 199 to thebattery lead 161, thence through battery B toground G. This last rotaryimpulse comes in While the 4side switch is in second position, and'atthesame time the differential relay-139 is-energized by the said rotaryimpulse, so that the diffel-ential relay springs 200'and 199 are incontact. After the connector is released, 'if the calling subscriberpresses his signaling' button 15 he grounds the vertical line conductorand energizes the vertical line relay 129 of the connector and alsoraises the connector switch-shaft, which latter, upon rising, close'sthe off-normal springs 231- and 232, thereby lestablishing a busy-signalthrough the callin substation. The busy signaling 'current ows from thesecondary winding of the busy 4coil 154 through the off-normall springs231 and 232 to the side switch wiper 137, thence through thecondenser233 to the calling substation and back over the vertical .sideof the line through the vertical line relay 129 to the battery lead 161and back tothe coil 154.

The condensers 234 and 233 are provided in the'connectorforseparatingthe calling section from the called section of the line ataI point between the line relays 130 and 129 vand the back-bridge relays142 and 143 for well-known reasons. `When the calling subscriber hearsthe busy signal he hangs 'up his receiver which operation grounds bothof the lineconductors 104 and 105 and simultaneouslyA energizes thevertical and rotary line relaysV y129 and 130 and the differential relay139, with the result already eX- plainedfthat is, withv the result thatall of the switches are released and restored to normal condition.Suppose that the sub station #110 is called by another substation, #120for example. Assume that the lished connection would then be the same asY that shown in Fig. 1,-eXcept that the trunk line leading to theconnector D would be connected with the line switch allotted to the line#120 instead of with the line switch A, as shown. In thatv case, if'asubscriber located on the line (as the subscriber #210 `is located) wereto remove his receiver and attempt tomake a call while the vline isbusy, the relay 2254would, of course, be energized over a circuitincluding the vertical normal conductor 101 and the vertical back- 1bridge coil 143 tothe battery B. vWhen one v subscriber has calledanother line, the re-- lease isthe same as the release alreadydescribed, and connection with the called line is severed as soon astheconnector Wipers are disengaged from the banks.

From the foregoing it will ba, seen .that

' we provide an improved telephiie system which is anv improvement onprior application Serial #270,591, led Julyl20, 1905, and in which arecombined a common battery and a lockout and individual switcharrangements for the party lines. Furthermore, we provide a lock-outrelay energizing circuit which includes the transmitter and whichincludes three switch points controlled by the switch-hook, two of thepoints (springs 26 and 27 'and springs 28 and 29) being normally openand the other one (springs 32 and 33) being normally closed. Thisenergizing circuit also includes the subscribers ringing key, by whichthe calling subscriber initiates 'the operations which result in theproduction of a call-signal at the called subscribers substation.-It.will also be seen that two private normal relays are employed in eachsubscribers vir'idividual switch, for'the purposes set forth, which re-Vlays are each bridged by a condenser.

Vhat we claim as our invention is ,1. The Ycombination of a plurality ofparty linesubstations, lock-out devices for the party line substations,a commo battery for supplying talking current t party line substations,anl automaticf.individual switch. allotted to the party linesubstations, a plurality of irsbselectors, and trunk lines leading fromthe' individual switch to the first-selectors.

and a microphone transmitter, and with a hook-switch having three switchpoints, two

of said points being normally open' and the Y third being normallyclosed, and a lock-out relay energizing circuit including the saidtransmitter and three switch points.

3, In a telephone system, a party-line, a

,plurality of party line substations thereon, a subscribers ringing keyfor each party line substation, a lock-out relay for each party linesubstation, and a lock-out relay energizing circuit for each substationincluding the ringing key thereof, said relays connected to only oneside of the line.

4. -The ycombination of a subscribers telephone line, an individualtrunking switch .for said line, .a plurality of first-selectors, trunklines leading from the individual switch to the 'rst-selectors, and aplurality of ,private normal relays in each of said trunk lines.l

5. The combination of a plurality of party line substations, lock-outdevices for the party line substations, a common battery for supplyingtalking current to the party line sub* stations, an automatic individualswitch allotted to the party line substations, a plurality offirst-selectors, trunk lines leading from the individual switch to theiirst-selec tors, and automatic connectors less in num-- ber than thesubscribers and each controllable by a calling subscriber for closingthe final connection with the called subscribers 6. The combination ofparty line substations each provided with a lock-out relay and amicrophone transmitter, and with a hoek-switch .havingthree switchpoints, 'two of saidpoints being normally open and the third beingnormally closed, a lock-out relay energizing circuit including the saidtransmitter and three switch points, and automatic connectors less innumber than the subscribers and each controllable by a call-ing sub'-scriber for closing the iinal connection with the called subscribersline.

7 The combination of party line substations,l a subscribers ringing keyfor each party lline substation, a lock-out relay for each party linesubstation, a lock-out relay energizing circuit for each substationincluding the ringing key thereof, and automatic connectors 4less innumber than the subscribers and each controllable by a callingsubscriber for closing the inal ,connection with the called subscribersline.

8. The combination of a subscribers telephone line, an individualtrunking switch for said line, a plurality of iirst-selectors, trunklines leading from the individual switch to the rst-selectors, aplurality of private normal relays in each of said trunk lines, .andautomatic connectors less in number than the subscribers and eachcontrollable by 'a calling subscriber for 'closing the inal connectionwith the called subscribers line.

9. The combination o-a plurality of party line substations, lock-outdevices for the party line substations, a common battery for supplyingtalkin-g current to the party line substations, an automatic individualvprogressively movable non-numerical switch allotted to the party linesubstations, a plu-` rality of automatic switches, and trunk linesleading from the individual switch to the automatic switches.

10. The combination of a subscriberstelethe party line substations, acommon battery v for supplying talking current to the party linesubstations, an automatic individual progressively movable non-numericalswitch,

allotted to the party line substations, connecting apparatus, andltrunkl lines leading from the'in'dividual switch to the connectingapparatus; f

l2. The combination of a subscribers telephone line, an individualtrunking switch 'for said line', connecting apparatus, trunk linesleading Jfrom the individual yswitchto the connecting apparatus, and aplurality of relays associated with each trunk line for controlling theyprivate normal circuit.

13. An automatic party line telephone exchange system, comprising commonbattery talking means, preliminary impulse means, trunks and automaticmeans for selecting them ahead of the calls, means re sponsive to thepreliminary impulse for seizing the preselected trunks, vand party-linelock-out means, substantially as set forth.-

lll. Ina system in which the trunks are divided into groups, thecombination of a plurality of party' line substations,lock-out devicesfor the party line sub-stations, a common `battery for supplying talkingcurrent to the party line substations, an automatic individual switchallotted to the party line substations, a plurality of first selectors,each selector havingV vertical motion to select ,Y groups and rotarymotion to find an idle trunk in any selected group, and trunk linesleading from the individual switch to the first selectors.

15. In a system in which the subscribers lines are divided into groups,the combination of party line substations each provided with a lock-outrelay f and a microphone transmitter, and with a hook-switch havingthree switch points, twoof said points being normally open and the thirdbeing normally closed, a lock-out relay energizing circuit including thesaid transmitter and three switch points,and means havingvertical-motion to. select groups `and rotary motion to ind the line ofthe called subscriber.

16. lIn a system in which the subscribers? llnes are divided intogroups, the combina.-

Aa. lock-out relay substation including the ringing'key there-l.frittata Vtion of party line s ubstations,a subscribers "ringing key`for each party line substation, a lock-out relay tor each party linesubstation., energizing circuit for each ot, and means having verticalmotion to select groups and rotary motion to lind the line of the calledsubscriber. ,u In a system` in which the trunks are divided into groups,the combination of a subscribers ltelephone line, an individual trunkingswitch for said line, a plurality of first selectors, each selectorhaving vertical motion to select groups and-rotary' motion to tind anidle trun trunk lines leading from yswitch to the first selectors, andaplurality ofv private normal rela-ys in each of said trunk lines l 118.In a system in which the trunks are 'divided into groups,.thecombination of a plurality of party line substations, lock-out devicesfor the party line'substations, a common battery for supplying talkingcurrent to the party line substations, an automatic individual switchallotted to the party line substations, a plurality of first selectors,each selector having vertical motion to select groups and rotarymotionto' lind an idle trunk in any selected group, trunk lines leading fromthe individual vswitch to theiirst selectors, and automa-tic connectorsless in number than the subscribers and each cou-l trollable 'by acalling subscriber for nding the called subscribers line.v

In a system in which the subscribers lines are divided into groups, thecombinationhof party line substationseach provided with "a lock-outrelay ,and a microphone transmitter, and with a hook-switch 'havingthree switch points, two of said points being normally openand the thirdbeing normally closed, a lock-out relay energizing circuit including thesaid transmitter and three switch s points, and automatic connectorsless in number than the' subscribers and each having vertical andlrotary motion controllable by a callingsubscriber for finding thegroupand line of the called subscriber.

i, 20. Ina system in which the subscribers" linesV are divided intogroups, the combina tion jofparty line substations, a subscribersringing key for each party line substation, a each party linesubstation,

substation including the ringing key thereH of, and automatic connectorsvless in number than the subscribers and each having-vertical and rotarymotion controllable by acalliiig subscriber for finding the group andline of the called subscriber.

21. In a system in which the subscribers? lines are divided into'groups, tbe combina"- tion of a subscribers telephone line, anindividual trunking switch for said line, a plu tscribers telephone ingswitch for said line, a plurality of.

and trunk rality of `hrstselectors, trunk lines leading from theindividual switch to the lirst selectors, a plurality of private normalrelays in each of said trunk lines, and automatic connectors lessfinvnumber than the subscribers and each having -vertical and rotarymotion controllable by acalling subscriber for linding the group andline ofthe 'called subscriber. f

22. In a system in'which the lines are dividedl into groups, thecombination of a plurality of party line substations, lock-out devicesfor the party line substations, a common battery for supplying talkingcurrent to the party line 'substations, an individual progressivelymovable non-numerical switch allotted to the party line substations, aplurality of automatic Switches,

groups and rotar motion to ind a line in any selected group, and trunk'lines leading from the individual switch' to the automatic switches.

23. In a system in which the lines arev di vided into groups, thecombination of a subV line, an individuall trunkautomatic switches,trunk lines leading from the 'individual switch to. the automaticswitches, each automatic switch having vertical motion' to lselectgroupsand rotary motion to ind a line in any. selected group, and aplurality of relays associated with each trunk line for controlling theprivate normal circuit.

24. In a system in which the trunks and subscribers lines are dividedintogroups, the combination of a plurality of party line substations,lock-'out devices for the party line substations, a common battery forsupplying talking current to the party line substations, an automaticindividual progressively movable'non-numerical switch allot-` ted to theparty line, connecting apparatus, lines leading from the individualkswitch to the connecting apparatus, said connecting apparatus havingvertical motion to iind groupsY and' rotary motion vto lind idle trunksand called lines.

ln a system in which 'the trunks and subscribers lines are divided intogroups, the combination of a subscribers telephone line, an individualtrunking'switcli for-said line, connecting apparatus, trunk linesleadingfrom tlie'individual switch to the connectiiig apparatus, and aplurality of relays associated with each trunk line for controlling theprivate 'normal circuit, said con! e ch automatic switch having vertical`motion to select f control b y any subscriber thereon, and com-1` `monbattery means for supplying current to l lock-out arrangement thel samethem ahead of the calls, means responsive tothe preliminary impulse forseizing the'- preselected trunks, means having both vertical and rotarymotion vfor extending 'the connection from a selected trunk, and party'line lock-out means, substantially as set iforth,

27. In a telephone system, a-party line, a therefor adapted to preventinterference between subscribers on line, common `Abattery means forsupplying current to the line for talking purposes, and a non-'numericaltrunking switch for said line'subject to control by any' callingsubscriber thereon for trunk- -ing the call in the direction of thecalled subscriber'.

- 28. .In a telephone-system, a." party line, lock-out relays for thesubstations thereon adapted' to prevent interferencebetweensubscribers'. on the same line, a non-numerical trunking switchor said line subject to the line Ji`or talking purposes. 29. In atelephone system, means for preventing a partyline,

thesubscribers on said line, trunks and means for selecting themahead'of the calls, means for supplying current to the line for talkingpurposes, and means whereby any calling lsubscriber on the line closesconnection with ya preselected trunkline.V y

30. In a'. telephone system, a party-#line provided with means forpreven ing interference between the subscribers thereon, a'

non-numerical trunking switch for said line, first and second selectors,and a connector,

l all controllable over' said line by aiiy sub'- l said line,` aplurality of trunk lines extend- `a pair of relays in af condenserl in aground coniiig from said switch, cluded'in said trunk lines, shunt ofeach ot said relays,

vnection for providing a guarding potential 'for said subscribei'jsline, and means where' by said relays control said ground connection.

33. In a telephone system, a talkingcircuit including a subscribersline, a non-numerical switch individual thereto, a pair of line wipersand a private normal wiper controlled by said switch, and a pair ofrelays serially included in the talking circuit :tor

serially includedA in .in shunt of each lof said rel'ays'to interferencebetween? rality of telephones -magnet at each telephone controlling anopcontrolling a ground. connection over said private normal conductor.

34. In a telephone system, a talking circuit including asubscribersline, a lnonvnumerical switch individual'thereto, a pair s* of linewipers and a private normal wiper controlled by said switch, a.pa1r ofrelays controlling a ground,v connection over said private normalconductor, anda condenser passage of" talking current therethrough.

. 35. In a telephone system,j"a telephone line, a plurality ofsub-stations for said line, a lock-oi'itjrelay for each telephone forpreventing one telephone from 'interfering with another, a separateenergizing circuit for each relay, and an operating circuit for eachtelephone,` the `lock-out relay of each tele- .phone controlling theoperating circuit of and a non-numerical switch its telephone,

the line controlling the cirassociated with 'cuits of all of tl'relock-out relays.

a telephone line,

36. In a telephone system,

for saidline, a

a plurality of sub-stations lock-out relay for each telephone forpreventing one telephone. from interfering with another, a separateenergizing circuit for each. relay, and an operating circuit for eachtelephone, the lock-out relay ot'each telephone controlling theoperating circuit of ,its telephone, and a non-numerical progressivelymovable switch associated with the line controlling the circuits of allthe lock- "out relays.

the talking circuit for permit theV 37. In a telephone system, atelephone line, 1

a plurality of sub-stations for said' line, a

loa'kfout :relay for eaehtelephone for preventingone telephone rominterfering with another, a separate energizing circuit for eachrelay,.and an. operating circuit for each telephone, the lock-out relayof eachtel'ephone controllingthe Voperating circuit of its telephone,anda progressively .movable non-numerical switch associated with the jline; and controlledover the operating circuit at each telephonecontrolling the cir. cuits of all of the. lock-out relays.:

38. 'In a telephone system, atelephone line, a plurality of sub-stationsforsaid line, a `lock-out relay for each venting one-telephone frominterferingwith another, a common '.battery for supplying' talkingcurrent to the substations on said v line, a progressivelymovablenon-numerical switch associated with said linecontrolling theenergizingcircuits ofsaid relays, and

for operating said means at each telephone switch to prepareanenergizing circuit for.

a plurality of said relays. 39. In a telephone system, a liiie,a pluforsaid line, alock-out erating circuit for its telephone, a non-nu?merical progressively movable switch for iso` 11,5 telephone for p reithe line, an energizing circuit at each telephone .for thelockoutanagnet associated therewith, a branch common-to all of saidcircuits and controlled by/said switch, means be operated during acall,'and means for' rendering the lock-out magnet of the callingtelephoneinoperativ'e during the same call. In a, telephone system, aline,l an automatic progressively movable non-numerical switch for saidline, a plurality of telephones for said line, an impulse sender foreach telephone for operating said switch over said line, anelectromagnetic lock-out mechi anism for eachA telephone 4for renderingits impulse sender inoperable, and a common .battery for supplyingtalking current to the telephones on;l said line. f

4l. In a telephone system, a line, an automatic lprogressively .movablenon-numerical switch for said line, a plurality of telephones for saidline, an impulse sender for each telephone for operating said switchover said line; an electromagnetic lock-out mechanism for each telephonefor rendering its impulse sender inoperable after any other telephone onthe line is operated, and a com* mon battery for supplying .talkingcurrent to the telephones on said line.

42. In a telephone system, a line, an-automatic progressively movablenon-numerical switchfor said line, Va plurality of telephones for saidline, an impulse sender for each telephonev for operating said switchover said line, an electromagnetic lock-out mechanism for .eachtelephone for rendering its impulse sender inoperable only after anothertelephone is operated, and a common 'battery for supplying talkingcurrent to the telephones on said line.

I8. In a telephone system, a line, an automatic progressively movablenon-numerical switch for said line, a plurality of telephones for saidline, an impulse sender forv each telephone for operating said switchover said line,an electromagnetic lock-out device-for each telephone, acircuit for each lock-out controlled b y the switch, each lockout whenoperated rendering the impulsev sender of. its telephone inoperative,and. a common battery for supplying talking current vto the telephoneson said line.

ll. In a telephone system, a line, an automatic progressively movablenon-numerical switch for said line, a plurality of telephones'for saidline, animpulse sender for each 'telephone for operating said switchover said line, an electromagnetic lock-out device for each telephone, acircuit for each lock-out controlled by the switch, each lockout whenoperated rendering the impulse sender of its telephone inoperative afterany lother telephone has operated the switch, and

a common battery for supplying talkingcurrentto the telephones on saidline.

In a telephone system, a line, an -auto-I matic progressively movable'nonnumerical switch for said line, a plurality of telephones forsaid-line, an impulse sender for each telephone for operating saidswitch over said line, an electromagnetic lock-out device for eachtelephone, a circuit for each locl-out controlled by the switch, eachlock-out when operated rendering the impulse sender of 4its telephoneinoperative only after any other telephone has operated the switch, anda common battery for supplying talking cur'-- rent` to thetelephones onsaid line.

4 6. In a telephone system, a line, an 'auto` matic progressivelymovable non-numerical switch for said line, a plurality of telephonesfor said line, an impulse senderffor each telephone for operating saidswitch over sa-id line, an electromagnetic lock-out device for eachtelephone, .a circuit for each lock-out controlled by the switch and thetelephone, anda common vbattery for supplying talking current to thetelephones on said line.

4-7. In a telephone system, a line,an aut0' matic progressively movablenon-numerical switch for said line,a plurality of telephones for saidline, an impulse sender for each telephone for operating saidswitch oversaid line, an electromagnetic'lock-out device 'for each telephone, acircuit for each 'lock-out controlled by the switch and the telephoneonly after anotlieiteleplioiie has Aoperated the switch, and a commonbattery for supplying talking currentto the telephones on said line. i

48. In a telephoneqsystem, a line, ani automatic progressively movablenon-numerical switch for said line, a plurality of telephones for saidline, an impulse sender for-each telephone for operating said switchover lsaid line, an electromagnetic lock-out mechanism for' eachtelephone for rendering its impulse sender inoperable, a normallyvinoperative circuit common to all said lock-out devices controlled bysaid switch and rendered `operativeV when the switch is operated, and anindividual branch for each lock-out controlled by its associatedtelephone to operate'r the loch-out after the switch has operated,

'and a common battery for supplying talking A for each telephone forrendering its impulse sender inoperable. a normally open circuit izoAcommon to all said lock-ont devices con-- trolled b vsaid switch tocli-se the same when the switch is operated, an Aindividual branch` foreach lock-out controlledby its associated current tothe telephones onsaid switch is operated,

each lock-out controlled telephone to operate theilock-out after thecomprising the line,

v"maticprogressively ,ing its impulse mally inoperative circuit commonto all telephone to operate the lock-out after the switch has closed thecircuit, anda common battery -for supplying talking current to thetelephones on said line.

In a telephone system, a line, an automatic progressively movablenon-numerical switch for said line, a plurality of telephones for saidline, an impulse sender for each telephone for operating said switchvover :said

line, an electromagnetic lock-out mechanism for each telephone forrendering its impulse sender inoperable, a normallyopen circuit commonto all said' lock-outI devicesl controlled by said switch to close thesame when the switch is operated, a normally open indi?, dividual branchfor each lock-out -mechanisin controlled by its associated telephone toclose an energizing circuit forthe lockout mechanism 'after the switchis operated, and acommon battery for supplying talking line.

51. In a'telephone system, a line, an automovable non-numerical switchfor said line, a plurality of telephones for said line, an impulsesender for each telephone for operating said switch over said line, anelectromagnetic lock-out mechanism' for each telephone for rendersenderinoperable, fa norsaid lock-out devices 4controlled by said switch andrendered operativev when the an individual branch for by vits associatedswitch has operated, said common circuit and a common battery forsupplying talking currentl to the' tele'- phones on said line. f

52. In a telephone system, a line, an auto matic progressively movablenon-numericalf switch for said, line, a plurality of telephones for saidline, an .impulse sender for each telephone Jfor operating saidswitchover vsaid line, an electromagnetic lock-out mechanism foreach telephonefor rendering its impulse sender inoperative, a nor- 'mally .opencircuit common to all said lockout devices controlle'dby saidy switch toclose thesame when the switch -is operated,

4-an individual branch Jr'or each lock-'out controlled'by its associatedtelephone to operate the -locleout after the switch has closed thecircuit, said common vcircuit comprising the line, and a 'common batteryfor supplying -talking vcurrent to the telephones on said. line.

53. In a ltelephonesystem, a line, an au. tomatic progressively movablenon-numerical switchlor said line, a plurality of telephones for saidline, an impulse sender'for each telephone `for `operating said switchover said line, an electromagnetic lock-out j telephone :for render-Avices controlled b-y said only one side of the line,

ing its impulse sender i` able," a normally open circuit comin toll'said lockout devices controlle s d .switch to close the same when thech-ifsoperated, a normally open individu.

lock-out mechanism controlled' its associated teleph'oneto close anenergizing?, circuit for thel lockout mechanism after the switch isoperated, said common circuit comprising the line., and a commonbatteryfor supplying talking current to the telephones on said line'.

54. In a telephone matic progressively movable switch 'for said line, aplurality phones for said line,

system, a line, an autonon-numerical of teleover said line, anelectromagnetic lock-out mechanism for each telephone for render--inoperable, a nor.

ing its impulse sender mally inoperative circuit common to all said-'lock-'out devices controlled by said switch matic progressively-movable non-numerical a plurality of tele` an impulse sender for switchfor said line, phones for said line, each telephone 'for operating 'saidswitch overl said line, an electromagnetic lock-out mechanism for eachtelephone forA rendering its impulse sender inoperable, a normally opencircuit common to all lsaid lock-out deswitch to close the an impulsesender for each telephone for operatingl said switchl ico saine when theswitch isoperated, an ind1.

vidual ,branchv for by its associated telephone to operate the lock-out.after the switch has closed. the circuit, said common circuitcomprisingonly each lock-out controlled one side of the line, and acommon battery orsupplying talking current to the telephones on saidline.` s

56. In a telephone system, a line, an automaticv progressively movablenon-numerical switch for said line, aphones for said line, an impulsesender for each telephone for operating said switch over said line, anelectromagnetic lock-out mechanism for each telephone for rendering itsimpulse sender inoperable, a normally open'circuit common to allsaidlock-out devices controlled by said switch to close the same whenthe switch is operated, a normally open individual branch for each locksout mechanism controlled by it's associated telephone to close anenergizing'circuit for ii54 plurality. of telethe lock-out mechanismafter theswitch isoperated, said common and a common batcircuitcomprising Llanera tery/for supplying talking current to the telephoneson said line. Y

57. In a telephone system, a line, an automatic progressively movablenon-numcrical switch for said line, a plurality of tele-- phones forsaid line, an impulse sender for each telephone for operating saidswitch vover said line, an electromagnetic lock-outmechanism Jfor each.telephone for render- 4controlled by v ing its impulsesender inoperable,a circuit common to all of saidlock-out'mechanisms said switch, anindividualbranch for each lock-,out mechanism controlled by itsassociated telephone, and a:

common battery for supplying talking current to the telephones on saidline.

58. In a telephone system,'a line, an auto matic progressively movablenon-numerical switch for said line, a plurality of Atelephones for saidline, an impulse sender for each telephone for operating said switchover said.line,' an electromagnetic 1ock-out mechanism for eachtelephone for rendering its 'impulse sender inoperable, a circuit commonto all of said lock-'out mechanisms controlled by said switch, anindividual vbranch for each lockout mechanism controlled by itsassociated telephone, said common circuit individual tothe line," and acommon battery for supplying talking current to the telephones on saidline.

59. In a telephone system, a line, an auto amatic progressively movablenon-numerical switch for'said line, a' plurality of telephones for saidline, an impulse sender for each telephone for operating' said switchoversaid line, an electromagnetic lock-out mechanism for each telephonefor rendering its 1m-v wpulse sender inoperable, a circuit common to.40.,

all of said lock-out mechanisms controlled Qby said switch, anindividualbranch for i each lockout mechanism controlled by' its associatedtelephone, said common circuit in- 5l ydividual to one side of the line,and a com-Y mon battery for supplying talking current to the telephoneson said line.

f 60. In a telephone system, a line, an automatic progressively movablenon-numerical switch for said line., a plurality of telephones for saidline, an impulse sender for each telephone for operating the switch oversaid line, an electromagnetic lock-outmech-v anism for each telephone,for rendering its impulse lsender "inoperable, a c1rcu1tcom -mon to allof said lock-out mechanisms controlled by said switch, an individualbranch circuit for each lock-out mechanism controlled by its telephonewhereby when the first telephone comes on the line to operate the switchits lockout does not operate, and whereby the other lock-out devices arerendered operablelv when any 4other telephone is brought on the line,whereby said other telephone is prevented from interfering, if itsimpulse mechanism is-operated, with the connection of the telephonepreviously on the line, and a common battery for supply:

ing talking current to the telephones on said line. l

61. The combination of a subscribers telephone line, an individualtrunking switch ffcr said line, a plurality of automatic switches, trunklines leading from the in-I dividual switch to the automatic switches,

and a plurality of relays in each trunk line forcontrolling the privatenormal circuit.

. 62. lThe combination of a subscribers telephone line, an individual.trunking switch for said line, connecting'apparatus, trunk linesleadingfrom the individual switch to the connecting apparatus, and aplurality of relays in each trunk line for controlling the privatenormal circuits.

63. ,In a system in. which the lines are divided intogroups, thecombination of a subscribers telephone line, an individual trunkingswitch for said line, a plurality of automatic switches, trunk linesleading fromthe individual switch to the automatic switches,

each; automatic switch having vertical motion to select groups and'rotary motion toI `trunk lines and called lines.

Signed by us at Chicago, Cook county, Illinois, this 15th day ofDecember, 1906.

ALEXANDER s. KEiTH. Tanner c. Maurin.

Witnesses:

EDWARD D. Fincas, ARTHUR B. Ernani?.

